Immune-Based Therapy in Triple-Negative Breast Cancer: From Molecular Biology to Clinical Practice.

Triple-negative breast cancer (TNBC) has been considered for many years an orphan disease in terms of therapeutic options, with conventional chemotherapy (CT) still representing the mainstay of treatment in the majority of patients. Although breast cancer (BC) has been historically considered a "cold tumor", exciting progress in the genomic field leading to the characterization of the molecular portrait and the immune profile of TNBC has opened the door to novel therapeutic strategies, including Immune Checkpoint Inhibitors (ICIs), Poly ADP-Ribose Polymerase (PARP) inhibitors and Antibody Drug Conjugates (ADCs). In particular, compared to standard CT, the immune-based approach has been demonstrated to improve progression-free survival (PFS) and overall survival (OS) in metastatic PD-L1-positive TNBC and the pathological complete response rate in the early setting, regardless of PD-L1 expression. To date, PD-L1 has been widely used as a predictor of the response to ICIs; however, many patients do not benefit from the addition of immunotherapy. Therefore, PD-L1 is not a reliable predictive biomarker of the response, and its accuracy remains controversial due to the lack of a consensus about the assay, the antibody, and the scoring system to adopt, as well as the spatial and temporal heterogeneity of the PD-L1 status. In the precision medicine era, there is an urgent need to identify more sensitive biomarkers in the BC immune oncology field other than just PD-L1 expression. Through the characterization of the tumor microenvironment (TME), the analysis of peripheral blood and the evaluation of immune gene signatures, novel potential biomarkers have been explored, such as the Tumor Mutational Burden (TMB), Microsatellite Instability/Mismatch Repair Deficiency (MSI/dMMR) status, genomic and epigenomic alterations and tumor-infiltrating lymphocytes (TILs). This review aims to summarize the recent knowledge on BC immunograms and on the biomarkers proposed to support ICI-based therapy in TNBC, as well as to provide an overview of the potential strategies to enhance the immune response in order to overcome the mechanisms of resistance.

A Dose-finding Study of Metronomic Oral Vinorelbine in Combination With Oral Cyclophosphamide and Bevacizumab in Patients With Advanced Breast Cancer.

BACKGROUND: Metronomic chemotherapy can induce disease control in patients with metastatic breast cancer (MBC) and has better safety profiles than conventional chemotherapy. Evidence suggests that cytotoxics can be anti-angiogenic in pre-clinical models and may have synergistic effects when combined with anti-vascular endothelial growth factor therapies. PATIENTS AND METHODS: Patients pretreated with ≥ 1 prior line of therapy for MBC received oral cyclophosphamide 50 mg daily in combination with oral vinorelbine at escalating doses of 20 mg (V20), 30 mg (V30), and 40 mg (V40) 3 times per week, and intravenous bevacizumab 15 mg/kg every 3 weeks. Patients with human epidermal growth factor receptor 2-positive disease were given the same regimen plus standard trastuzumab. Doses were escalated when 3 patients completed 3 treatment cycles of V20 and V30, without experiencing dose-limiting toxicities. The recommended dose was then tested in a further 6 patients. Circulating tumour cells and circulating endothelial cells (CEC) were measured in 30 mL of whole blood samples at baseline, after cycle 1, and at the disease progression. RESULTS: Fifteen patients were recruited from June 2013 to October 2015. The median age was 61 years (range, 29-72 years); 80% had estrogen receptor-positive and 33% had human epidermal growth factor receptor 2-positive disease. At least 67% had visceral metastases, and 80% had received ≥ 2 lines of prior treatment. No dose-limiting toxicities were observed at the 3 dose-levels, making V40 the recommended dose. Overall 8 (53%) patients developed grade 2 adverse events (arthralgia, n = 3 [20%]; asthenia, n = 2 [13%]; diarrhea, n = 2 [13%]; leukopenia, n = 2 [13%]). Bevacizumab was associated with grade 3 hypertension (n = 3 [20%]). Stable disease as best response was observed in 11 (73.3%) patients. The clinical benefit rate was 66.6% (10/15 patients). The median time to progression was 6.9 months. At baseline, CECs were more commonly detectable than circulating tumor cells; however, no statistical correlation was found between CEC kinetics and response. CONCLUSION: A metronomic vinorelbine dose of 40 mg combined with cyclophosphamide and bevacizumab is a promising treatment regimen in pretreated patients with MBC.

Impact of COVID-19 outbreak on cancer immunotherapy in Italy: a survey of young oncologists.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has overwhelmed the health systems worldwide. Data regarding the impact of COVID-19 on cancer patients (CPs) undergoing or candidate for immune checkpoint inhibitors (ICIs) are lacking. We depicted the practice and adaptations in the management of patients with solid tumors eligible or receiving ICIs during the COVID-19 pandemic, with a special focus on Campania region. METHODS: This survey (25 questions), promoted by the young section of SCITO (Società Campana di ImmunoTerapia Oncologica) Group, was circulated among Italian young oncologists practicing in regions variously affected by the pandemic: high (group 1), medium (group 2) and low (group 3) prevalence of SARS-CoV-2-positive patients. For Campania region, the physician responders were split into those working in cancer centers (CC), university hospitals (UH) and general hospitals (GH). Percentages of agreement, among High (H) versus Medium (M) and versus Low (L) group for Italy and among CC, UH and GH for Campania region, were compared by using Fisher's exact tests for dichotomous answers and χ2 test for trends relative to the questions with 3 or more options. RESULTS: This is the first Italian study to investigate the COVID-19 impact on cancer immunotherapy, unique in its type and very clear in the results. The COVID-19 pandemic seemed not to affect the standard practice in the prescription and delivery of ICIs in Italy. Telemedicine was widely used. There was high consensus to interrupt immunotherapy in SARS-CoV-2-positive patients and to adopt ICIs with longer schedule interval. The majority of the responders tended not to delay the start of ICIs; there were no changes in supportive treatments, but some of the physicians opted for delaying surgeries (if part of patients' planned treatment approach). The results from responders in Campania did not differ significantly from the national ones. CONCLUSION: Our study highlights the efforts of Italian oncologists to maintain high standards of care for CPs treated with ICIs, regardless the regional prevalence of COVID-19, suggesting the adoption of similar solutions. Research on patients treated with ICIs and experiencing COVID-19 will clarify the safety profile to continue the treatments, thus informing on the most appropriate clinical conducts.

Plasma Thymidine Kinase Activity as a Biomarker in Patients with Luminal Metastatic Breast Cancer Treated with Palbociclib within the TREnd Trial.

PURPOSE: Thymidine kinase 1 (TK1) is downstream to the CDK4/6 pathway, and TK activity (TKa) measured in blood is a dynamic marker of outcome in patients with advanced breast cancer (ABC). This study explores TK1 as a biomarker of palbociclib response, both in vitro and in patients with ABC. EXPERIMENTAL DESIGN: Modulation of TK1 levels and activity by palbociclib were studied in seven estrogen receptor-positive breast cancer cell lines: sensitive (PDS) and with palbociclib acquired resistance (PDR). TKa was assayed in plasma obtained at baseline (T0), after one cycle (T1), and at disease progression on palbociclib (T2) in patients enrolled in the "To Reverse ENDocrine Resistance" (TREnd) trial (n = 46). RESULTS: Among E2F-dependent genes, TK1 was significantly downregulated after short-term palbociclib. Early TKa reduction by palbociclib occurred in PDS but not in PDR cells. In patients, median TKa (mTKa) at T0 was 75 DiviTum units per liter (Du/L), with baseline TKa not proving prognostic. At T1, mTKa decreased to 35 Du/L, with a minority of patients (n = 8) showing an increase-correlating with a worse outcome than those with decreased/stable TKa (n = 33; mPFS 3.0 vs 9.0 months; P = 0.002). At T2, mTKa was 251 Du/L; patients with TKa above the median had worse outcomes on post-study treatment compared with those with lower TKa (2.9 vs 8.7 months; P = 0.05). CONCLUSIONS: TK is a dynamic marker of resistance to palbociclib which may lead to early identification of patients in whom treatment escalation may be feasible. In addition, TKa may stratify prognosis in patients with acquired resistance to palbociclib.

The Emerging Role of ESR1 Mutations in Luminal Breast Cancer as a Prognostic and Predictive Biomarker of Response to Endocrine Therapy.

Mutations in the hotspot ligand-binding domain of the estrogen receptor (ER) gene ESR1 have recently been recognized as mechanisms of endocrine resistance in endocrine receptor-positive metastatic breast cancer (MBC). Accumulating data suggest these mutations develop under the selective pressure of endocrine treatments, and are infrequent in untreated ER-positive breast cancers. In vitro studies show that these mutations confer ligand-independent activity, resistance to estrogen deprivation, and relative resistance to tamoxifen and fulvestrant. Post-hoc retrospective and prospective analyses of ESR1 mutations in patients with MBC have consistently found that these mutations are markers of poor prognosis and predict resistance to aromatase inhibitors (AIs). These results warrant further investigation and prospective validation in dedicated studies. Moreover, studies are ongoing to clarify the activity of novel drugs in the context of metastatic endocrine resistant luminal breast cancer harboring ESR1 mutations. In this review, we summarize the pre-clinical and clinical findings defining the characteristics of ESR1 mutant breast cancer, and highlight the potential clinical developments in this field.

Mechanisms of Resistance to CDK4/6 Inhibitors: Potential Implications and Biomarkers for Clinical Practice.

The recent arrival of CDK4/6 inhibitor agents, with an approximate doubling of progression-free survival (PFS) associated with their use in hormone receptor-positive, HER2-negative advanced breast cancer (BC), has radically changed the approach to managing this disease. However, resistance to CDK4/6 inhibitors is considered a near-inevitability in most patients. Mechanisms of resistance to these agents are multifactorial, and research in this field is still evolving. Biomarkers with the ability to identify early resistance, or to predict the likelihood of successful treatment using CDK4/6 inhibitors are yet to be identified, and represent an area of unmet clinical need. Here we present selected mechanisms of resistance to CDK4/6 inhibitors, largely focussing on roles of Rb, cyclin E1, and the PIK3CA pathway, with discussion of associated biomarkers which have been investigated and applied in recent pre-clinical and clinical studies. These biological drivers may furthermore influence clinical treatment strategies adopted beyond CDK4/6 resistance.

Strain-oriented strategy for guiding cardioprotection initiation of breast cancer patients experiencing cardiac dysfunction.

AIMS: This study assessed the impact of the strain-guided therapeutic approach on cancer therapy-related cardiac dysfunction (CTRCD) and rate of cancer therapy (CT) interruption in breast cancer. METHODS AND RESULTS: We enrolled 116 consecutive female patients with HER2-positive breast cancer undergoing a standard protocol by EC (epirubicine + cyclophosphamide) followed by paclitaxel + trastuzumab (TRZ). Coronary artery, valvular and congenital heart disease, heart failure, primary cardiomyopathies, permanent or persistent atrial fibrillation, and inadequate echo-imaging were exclusion criteria. Patients underwent an echo-Doppler exam with determination of ejection fraction (EF) and global longitudinal strain (GLS) at baseline and every 3 months during CT. All patients developing subclinical (GLS drop >15%) or overt CTRCD (EF reduction <50%) initiated cardiac treatment (ramipril+ carvedilol). In the 99.1% (115/116) of patients successfully completing CT, GLS and EF were significantly reduced and E/e' ratio increased at therapy completion. Combined subclinical and overt CTRCD was diagnosed in 27 patients (23.3%), 8 at the end of EC and 19 during TRZ courses. Of these, 4 (3.4%) developed subsequent overt CTRCD and interrupted CT. By cardiac treatment, complete EF recovery was observed in two of these patients and partial recovery in one. These patients with EF recovery re-started and successfully completed CT. The remaining patient, not showing EF increase, permanently stopped CT. The other 23 patients with subclinical CTRCD continued and completed CT. CONCLUSION: These findings highlight the usefulness of 'strain oriented' approach in reducing the rate of overt CTRCD and CT interruption by a timely cardioprotective treatment initiation.

Cyclin-Dependent Kinase 4/6 Inhibitors in Neoadjuvant Endocrine Therapy of Hormone Receptor-Positive Breast Cancer.

The landscape of therapeutic options for the treatment of hormone receptor (HR)-positive (HR+) HER2- breast cancer (BC) has been profoundly changed by the introduction of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors into the metastatic setting. Currently all CDK4/6 inhibitors are approved only in the metastatic setting by Food and Drug Administration (FDA) and European Medicine Agency (EMA), whereas their role in the neoadjuvant setting is still at an investigational stage. Exploitation of novel agents such as CDK4/6 inhibitors to improve the efficacy of neoadjuvant endocrine therapy (ET) or to overcome de novo resistance to ET is an area of research under active evaluation. We present a review of the currently available data and ongoing clinical trials that are evaluating the role of CDK4/6 inhibitors in neoadjuvant therapy of HR+ HER2- early BC, and also illustrate translational aspects, such as the potential biomarkers of response to these new therapeutic agents.

The optimal duration of adjuvant endocrine therapy in early luminal breast cancer: A concise review.

Patients with luminal early breast cancer are at risk of relapse, even after five years of adjuvant endocrine therapy. To date, no biomarkers have been clinically validated to identify those patients at risk of late recurrence, who might benefit from extended adjuvant endocrine therapy. In recent decades, multiple clinical trials have tested the role of extending adjuvant endocrine therapies in patients with luminal disease. However, the data currently at our disposal are conflicting. This article reviews all the major trials concerning extended adjuvant endocrine regimens, and formulates some general conclusions and hypotheses of future study.

CDK 4/6 Inhibitors as Single Agent in Advanced Solid Tumors.

Cyclin-dependent kinases (CDK) 4/6 inhibitors, namely abemaciclib, palbociclib, and ribociclib, interfere with cell cycle progression, induce cell senescence and might promote cancer cell disruption by a cytotoxic T cells-mediated effect. Phase III randomized clinical trials have proven that CDK4/6 inhibitors (CDK4/6i) in combination with several endocrine agents improve treatment efficacy over endocrine agents alone for hormone receptor positive (HR+) HER2 negative (HER2-) metastatic breast cancer (MBC). Based on such results, these combinations have been approved for clinical use. Preclinical studies in cell cultures and mouse models proved that CDK4/6i are active against a broad spectrum of solid tumors other than breast cancer, including liposarcoma, rhabdomyosarcoma, non-small cell lung cancer, glioblastoma multiforme, esophageal cancer, and melanoma. The role of CDK4/6i in monotherapy in several solid tumors is currently under evaluation in phase I, II, and III trials. Nowadays, abemaciclib is the only of the three inhibitors that has received approval as single agent therapy for pretreated HR+ HER2- MBC. Here we review biological, preclinical and clinical data on the role of CDK4/6 inhibitors as single agents in advanced solid tumors.

Fractional microablative CO2 laser in breast cancer survivors affected by iatrogenic vulvovaginal atrophy after failure of nonestrogenic local treatments: a retrospective study.

OBJECTIVE: Vulvovaginal atrophy (VVA) is a condition frequently observed in menopause. Its symptoms can significantly affect the quality of life of patients. Since VVA is related to estrogen deficiency, chemotherapy and hormone therapy for breast cancer (BC) might cause VVA by inducing menopause. Given the lack of effective treatment for VVA in BC survivors, we retrospectively evaluated the efficacy and tolerability of fractional microablative CO2 laser therapy in these patients. METHODS: We treated 82 BC survivors with three cycles of CO2 laser after failure of topical nonestrogenic therapy. The severity of symptoms was assessed with a visual analog scale (VAS) at baseline and after completion of laser therapy. Differences in mean VAS scores of each symptom before and after treatment were assessed with multiple t tests for pairwise comparisons. Multivariate analyses were used to adjust the final mean scores for the main confounding factors. RESULTS: Pre versus post-treatment differences in mean VAS scores were significant for sensitivity during sexual intercourse, vaginal dryness, itching/stinging, dyspareunia and dysuria (P < 0.001 for all), bleeding (P = 0.001), probe insertion (P = 0.001), and movement-related pain (P = 0.011). Multivariate analyses confirmed that results were significant, irrespective of patients' age and type of adjuvant therapy. CONCLUSION: This study shows that CO2 laser treatment is effective and safe in BC patients with iatrogenic menopause. However, the optimal number of cycles to administer and the need for retreatment remain to be defined. Prospective trials are needed to compare CO2 laser therapy with therapeutic alternatives.